The present invention concerns the technology which displays the object shape created by the given shape generating system and/or equipment in virtual space, that is the computer world, in order to make a reduction of the target object into real space, that is the physical world, and the technology which realizes what is called virtual reality including the simulation technique.
Of course, the present invention is positioned as the technology which includes the field related to the video image generating technology, for example, as the technology which fulfills the roll to say that the rebuilt image can be made by information projected as the target object in the real world based on information in virtual space through shape input devices.
Namely, the present invention is the interface technology which constructs the cross link between the real world and virtual space, and not only the virtual reality generating technology for the world of the multi-media in a strict sense but also the indispensable one for the general presentation technology, especially the communication with the image in Internet, etc. Incidentally, the present invention is regarded as a basis technology of what is called VRML (Virtual Reality Modeling Language) in the field of the communication technology concerning information of the image. Therefore, a more usable, effective and efficient communication tool can be offered in mechanical communication for the multimedia environment, etc.
Moreover, the present invention provides a more freely constructive means and an efficient tool for bi-direction games, etc. in the complicated execution environment, making it possible to offer a more efficient and comfortable environment for developing and generating video game software. In addition to the field of the former technology, the present invention plays an important role in the technology effectively applicable for not only CAD and/or CAM, but also medical fields as an innovative supporting technology of a diagnostic technique by the visual image.
FIG. 9 shows the principle of xe2x80x9cray tracingxe2x80x9d, which is one of the conventional techniques of the rendering method. By this method, the 3D image of target object shapes is displayed on a display screen.
In the ray tracing method, a curved surface body as shown in FIG. 9 can be expressed according to a kind of analytic function, and an intersecting point on the target body can be naturally decided with a straight line (a line-of-sight or a view line) which passes through setting viewpoint E and given function which represents the surface of the target shape.
In this method, the image of the target shape is formed by a cluster of these pixels as a projecting position of the target shape corresponding with surface composing points on the target body with respect to pixels in which intersecting points exist. An intersecting point is determined between the straight line and function represented as the quadric surface when the target shape is regarded as the quadric surface. In this case, the intersecting point decision problem means the solution of the quadratic equation. It is an approximate means of algebraically solving a problem to solve the quadratic equation for determining the intersecting point, and so the target shape can be essentially limited to the quadric surface. Naturally, the higher order (over the 2nd order) curved surface of the target shape cannot be realistically dealt with because of the difficulty in solving equations over the 2nd order related to the prior art, for example, the 3rd order equation. Therefore, in regards to general shapes, the rendering technique is required for an approximate curved surface and the complicated and difficult shape process is also required.
Thus, in the prior art, there are some big problems. For example, one problem is that the extreme limit of applied shape conditions might exist when the ray tracing method is applied. Another is that the calculating efficiency and the picture quality are very low in this method.
In the conventional ray tracing method, it is necessary to decide a normal line (or merely called xe2x80x9cnormalxe2x80x9d) at the intersecting point between a line-of-sight and display screen in order to determine the ray locus represented as a straight line, that is propagation of the light, and its luminosity. Except for the special case like a spherical surface, a normal line can be obtained by differentiating the analytic function which expresses the curved surface. In this case in which the intersecting point is obtained, the more difficult problem on a differential operation of function must be caused.
Obviously, the ray can be usually decided based on the reflection and/or the refraction of the light which is calculated with a normal line as a standard method, and a surface point of the target shape existing on the line of the ray defined as the passing locus of the ray can be determined by the same technique of examining the intersecting point in a view line. There is also the same problem when a surface point of the target shape existing in a line of ray is determined.
In the ray tracing method, fundamentally, the determining process must be continued as long as a shape composing point exists in the passing locus of ray. Therefore, in this method, the above calculating and determining process must be also repeated against all pixels on a display screen. Because of the reason related as above, the calculating efficiency become lower and lower if more reality of the target image is needed, and so the dynamic rendering process can be almost impossible.
As another rendering technique, the polygon smoothing method is well known as well as the ray tracing method. As for the ray tracing method, a target shape of virtual space is faithfully formed by tracing along the locus of ray propagation as an image because this ray tracing method accurately constructs the situation of the real world projected by light, while the polygon smoothing method is a concise method considerably simplified with respect to the passing locus which propagates light. In the polygon smoothing method, a 3D shape body can be expressed as a polyhedron, and so this method is applied for only the polygon which is the component of a polyhedron-like shape. That is to say, for example, using the polygon smoothing method, a curved surface can be constructed as a mere aggregate of the minute plane because a curved surface can be expressed as an approximate polyhedron with the closed density of the minute planes.
For the polyhedron with a closed density, it is theoretically possible to apply the ray tracing method. Naturally, it is possible that a formulated equation is established when the intersecting point between a straight line and minute plane which composes the polyhedron should be obtained.
However, a number of the above composing planes of a polyhedron is required in order to raise the higher degree of approximation of the expression as a polyhedron, and a higher density of said composing plane of polyhedron body is necessary. The calculation under the condition as related above is impractical because the amount of the calculation can be enormous when the calculation of the polygon smoothing method is applied in the polyhedron with the higher density of composing planes.
It is naturally concluded that the polygon smoothing method might be applied as the rendering method without considering the degradation of image quality to be formed in order to break through the above problems and as an alternative method for the ray tracing method to be devised in order to clear the limit of the target shape processed by the ray tracing method.
In the meantime, the polygon smoothing method is due to such a method as processing based on the plain-like shape which constructs a surface of a polyhedron and projecting shape which composes the points of the polyhedron on a display screen by means of the clairvoyance and projection method. The shape image with surface composing points of the projected polyhedron is clearly made up as a line-like image. It becomes with the essential that the normal line on a surface composing the point must be obtained in order to convert the line-like image, that is the drawing image, into the plane-like image, that is the painting image. The normal line of the vertex of the polyhedron body is determined as an average of a normal line of the plane which surrounds the vertex because it cannot be compulsorily decided in the case of determining a real normal line of the plane. The method for deciding the normal line of the vertex as an average line is shown in FIG. 10(1).
Though the reflection and/or the refraction of the light can be discussed as the normal line of the vertex determined by the approximation method) the average normal line with respect to the average method can be given instead of the luminosity on a display screen pixel corresponding to the surface composing point of the target shape with the purpose of improving picture quality immediately. Each of the normal lines in proportion to the pixel can be determined as the 1st interpolation using the given average line.
A normal line is determined along the scanning line (the scan-line)of a display screen when the normal line is determined by the 1st interpolation. FIG. 10(2) shows the linear interpolating method on the normal line done by scanning. The luminosity calculation is carried out in the spatial position corresponding to the pixel after the normal line to the pixel is determined. In the case of the polygon smoothing method, the luminosity calculation is carried out as well as doing in the ray tracing method. Though the luminosity is calculated after placing a light source in a space, said ray locus calculation and its integrated evaluation are not executed as a rule.
As a result of this calculation frame, each of the pixel can be given the luminosity calculated as the 0th (zero) order ray propagation related as above, and the plane-like image is formed. As described above, the calculation process is complicated, and so the improvement of calculating efficiency cannot be expected. Therefore, generally, the trade-off operation should be done in the above calculation based on the relationship between calculating efficiency and picture quality. Namely, the number of composing planes of a polyhedron is suppressed in order to improve the calculating efficiency. Picture image quality deteriorates because the target polyhedron is constructed as the rough body and the expression accuracy gets the worse when the number of said planes are suppressed in such a way as related above. Therefore, in the situation forming the image which exceeds the limit of the trade-off, though the mapping technique which is expected to overcome what the above method lacks is used as a usual way, there is still a problem of frequently hurting the realistic feeling for the shape image, because the picture quality is not improved essentially.
The object of the present invention is to provide the presentation method of the 3D shape with remarkable improvement for both the calculation efficiency and picture quality, in other words, a higher speed and better quality of the picture image, when the 3D shape is displayed.
The present invention relates to a 3D shape presentation method that comprises:
a view point and display screen setting step for setting a view point and a display screen in a space in which a target object exists, according to a pixel position on the display screen that corresponds to the detected shape composing point,;
a direction of view (a line-of-sight) setting step for setting a line-of-sight from the view point;
a composing point of the target shape detecting step for detecting a shape composing point near a line-of-sight, in other words a view line; and
a target shape image constructing step for constructing a target shape image on the display screen by way of using a pixel position, which corresponds to the detected shape and is on the display screen, as a projecting point of the target shape.
Furthermore, the present invention also relates to a 3D shape presentation method that comprises:
a light source setting step for setting required light sources in a target object existing space;
an optical wide path pathway) setting step for setting an optical wide path with the detecting region around a line of rays, which has the power of detecting the shape composing point near a line of rays;
a shape composing point detecting step for detecting the composing point existing in the optical path;
a projecting 3D target shape displaying step for displaying a 3D shape on a screen by deciding the radiation strength of the shape composing points and giving the decided radiation strength to the pixel while all of said optical paths are decided by each of the displaying pixels as the controlling point.